This invention generally relates to an apparatus for evaluating a lens, and specifically relates to an apparatus for measuring the aberration of a lens.
Some semiconductor devices are fabricated by use of a light exposure system which projects a fine semiconductor pattern on a semiconductor wafer. Generally, lenses used in such a light exposure system are required to have a high resolving power. For example, a required resolving power is 1 micrometer or less, and corresponds to 500 lines/mm or higher in spatial frequency.
There are various prior art apparatuses for evaluating a lens. The prior art apparatuses are generally inadequate in accuracy for a high-resolution lens. Accordingly, an accurate apparatus for evaluating such a high-resolution lens has been desired.